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Clark et. al. 2003 USGS Open File Report 03-395
Spectral Library splib05a Sample Description

(For further information on spectrsocopy, see: http://speclab.cr.usgs.gov)

TITLE: Arsenopyrite HS262-3B DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS262-3B

MINERAL_TYPE: Sulfide

MINERAL: Arsenopyrite

FORMULA: FeAsS

FORMULA_HTML: FeAsS

COLLECTION_LOCALITY: Gold Hills, Utah

ORIGINAL_DONOR: Hunt and Salisbury Collection

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Spectra for this sample were originally published in: Hunt, G.R., J.W. Salisbury, and C.J. Lenhoff, 1971, Visible and near-infrared spectra of minerals and rocks: IV. Sulphide's and sulphate's. Modern Geology, v. 3, p. 1-14. With the note: "This sample is contaminated with some quartz and a small amount of pyrite and elemental sulphur. Arsenopyrite is opaque and spectrally featureless. Its opacity is caused by the conduction band extending over the entire range, mainly due to the presence of arsenic. The contaminants in this sample are not abundant enough to alter this behavior, and the fact that the largest particle size falls approximately in the middle of its reflectivity range has no real significance." Sample measured for the library was the 74-250Ám sieve interval.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA, 7.0-9.5 keV File: arsn263.mdi, *.out (smear mount on quartz plate) References: JCPDS #42-1320; Huebner's reference patterns Found: Quartz, arsenopyrite, un-indexed weak to very weak reflections at 6.3, 4.5, 3.42, 3.18, 2.86, and 2.75 angstroms Comment: Quartz reflections of moderate intensity (the (100) peak of nominal relative intensity 22% did not exceed 200 counts.sec-1), arsenopyrite reflections much weaker. Un indexed reflections could not be identified, suggesting they may represent more than one phase. Peaks are symmetric and of normal width, but alpha1-alpha2 wavelength resolution is poor. Phases are only moderately crystalline.

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: NONE #XRF, EM(WDS), ICP(Trace),WChem

COMPOSITION_TRACE:

None

COMPOSITION_DISCUSSION:

None

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

avg. grain size = 265Ám for arsenopyrite 59 vol% quartz 40 vol% arsenopyrite 1 vol% elemental sulfur Optically opaque, grayish yellow metallic luster. Suggest magnetic separation be done on this sample. G. Swayze.

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

None END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1c2_3_4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns

LIB_SPECTRA_HED: where Wave Range Av_Rs_Pwr Comment
LIB_SPECTRA: splib04a r 583 0.2-3.0µm 200 g.s.= 265 µm
LIB_SPECTRA: splib05a r 1225 0.2-3.0µm 200 g.s.=


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